Celtic eased past Albion Rovers at Excelsior Stadium and into the fifth round of the Scottish Cup.

Scott Sinclair's class separated the teams at half-time, as he found the top corner from the edge of the box with a stunning finish.

Celtic finished strongly and Dedryck Boyata headed off the bar before Moussa Dembele made it two when he turned home Scott Brown's cut-back.

Stuart Armstrong added a late third with a tap-in.

Width works for Celtic

Albion Rovers' approach was to try to crowd Celtic out. With the home side's defence sitting so deep, Celtic's most effective attacking ploy was to overload the flanks.

James Forrest, on the right, and Sinclair, on the left, encouraged this to happen by driving infield to make space for Cristian Gamboa and Kieran Tierney to surge beyond them from full-back.

Sinclair and Forrest saw plenty of the ball, with their movement and trickery a constant threat for the Albion defenders to contend with.

Sinclair saw one effort well blocked by Albion goalkeeper Ross Stewart before he made the breakthrough. His goal was a brilliant piece of improvisation, looping the ball over Stewart, who would have thought the ball was going over before it dipped sharply into the top corner.

Sinclair also created a chance for Forrest after the break, but the left-foot shot was stopped at the second attempt by Stewart. Gamboa also tried his luck from 20 yards but pulled his shot wide.

Albion apply themselves

Kieran Tierney (right) made his return to the Celtic team for the first time since October

The home side only had one viable game plan to employ: defending deep, with the back four narrow to protect the penalty box and five players strung across midfield, to reduce the space for Celtic to attack into.

The ploy worked, since Celtic seldom managed to work the ball behind the defensive line, which was well marshalled by the Dunlop brothers, Ross and Michael, in central defence. The drawback was that the home side were unable to build passages of possession to ease the pressure they were under.

Paul Willis and Ross C Stewart swapped between the centre-forward and right-wing positions throughout the game, but were always isolated when up front. The midfield three of Gary Fisher, Mark Ferry and Ross Davidson worked manfully, but mental and physical fatigue became a factor.

As Celtic penned them in during the second half, Boyata headed off the crossbar and Jozo Simunovic's effort from close range was hacked off the line by Ross Dublin.

Armstrong adds dynamism

With Brown and Nir Bitton sitting deep in midfield, Armstrong had licence to surge forward from a more advanced position.

Hard running has been a feature of his play this season, and the energy and vitality of Armstrong's display was important to maintaining Celtic's intensity. He delivered a fierce shot in the first half that Stewart tipped over and he swept another effort towards goal after the break, but the ball flew above the bar.

Even when Armstrong was not bursting beyond the attackers, the threat was still posed. One run by Brown into the penalty area ended with his cut-back being converted by Dembele.

In the final stages, Armstrong jinked past two challenges on the edge of the area before drilling a shot on target that Stewart saved. Moments later, he would not be denied, clipping the ball high into the net from close range.